Fix a traceback when a group has no name and a crash when dns gets interrupted

- http://pastebin.archlinux.fr/449676

src/poezio.py

@@ -33,8 +33,15 @@ def main():
     cocore = singleton.Singleton(core.Core)
     signal.signal(signal.SIGHUP, cocore.sighup_handler) # ignore ctrl-c
     cocore.start()
+    try:
         if not cocore.xmpp.start():  # Connect to remote server
             cocore.on_failed_connection()
+    except:
+        cocore.running = False
+        cocore.reset_curses()
+        print("Poezio could not start, maybe you tried aborting it while it was starting?\n"
+                "If you think it is abnormal, please run it with the -d option and report the bug.")
+    else:
         cocore.main_loop()    # Refresh the screen, wait for user events etc
 
 if __name__ == '__main__':

src/roster.py

@@ -95,7 +95,15 @@ class Roster(object):
 
     def get_groups(self, sort=''):
         """Return a list of the RosterGroups"""
-        group_list = sorted(filter(lambda x: bool(x), self.groups.values()), key=lambda x: x.name.lower())
+        group_list = sorted(
+                filter(
+                    lambda x: bool(x),
+                    self.groups.values()
+                ),
+                key=lambda x: x.name.lower() if x.name else ''
+            )
+
+        log.debug("Current groups: %s", group_list)
 
         for sorting in sort.split(':'):
             if sorting == 'reverse':